Process for making polyvinyl alcohol fibers having improved properties



commercial importance. have an affinity for the acid group contained in the fiber.

United States Patent 3,234,160 PROCESS FOR MAKING POLYVINYL ALCOHOL FIBERS HAVING IMPROVED PROPERTIES Kanji Matsubayashi, Kurashiki, Japan, assignor of onefourth to Air Reduction Company, Incorporated, New York, N.Y., a corporation of New York, and threefourths to Kurashiki Rayon Co., Ltd., Okayama Prefecture, Japan, a corporation of Japan No Drawing. Filed July 15, 1960, Ser. No. 42,997 Claims priority, application Japan, July 16, 1959, 34/ 22,797 3 Claims. (Cl. 260--29.6)

This invention relates to a method for producing fibers of polyvinyl alcohol which have improved dyeability.

As is well known, fibers derived from polyvinyl alcohol, known commercially as Vinylon, and produced by spinning from an aqueous solution of polyvinyl alcohol followed by formalization after heat-treatment, have insufiicient dyeability, and many attempts have been made to improve this property. Although the problem of providing sufficient dyeability in the case of acid wool dyes and direct cotton dyes has been generally solved by methods such as animalization, these methods are accompanied by disadvantages such as the fact that the introduced basic nitrogen tends to cause yellowing upon heating or prolonged use of the fiber. Even these methods, therefore, leave substantial room for improvement. Basic dyes heretofore in use are bright in color, but they lack light fastness, and similar desirable characteristics and they are not, therefore, of commercial importance at this time. Cation dyes have, however, recently been proposed as dyes for acrylic fibers such as Orlon, and the like, and these dyes have been found to have an improved light These dyes have thus become of substantial It is believed that these dy'es fastness.

In connection with fibers of polyvinyl alcohol, for example, as shown in the co-pending application of Keniche Tanabe et al., Ser. No. 787,386, filed January 19, 1959,

now Patent No. 3,023,182, it has been found that their afiinity for basic dyes can be increased by spinning the fibers from a mixture of polyvinyl alcohol and awatersoluble polymer containing a sulfo group. However, it has become apparent that when such a water-soluble poly- -mer is used, if acetalization is carried out by means of tive to increase the strength and elasticity of the fibers.

It is thus an object of this invention to provide a process for producing fibers of polyvinyl alcohol having high hotwater resistance and heat-resistance and desirable mechanical properties at least equal to known commercial polyvinyl alcohol fibers, yet characterized by a particular- 1y high dyeability, particularly with respect to silk dyes, such as basic dyes, cation dyes, and the like, and with respect to dyes proposed for acrylic-type fibers.

In accordance with this invention, spinning of fibers is efiected from a spinning fluid prepared by dispersing in a water solution of polyvinyl alcohol an emulsion or fine powder of a water-insoluble polymer containing an acid radical such as a carboxyl group of a sulfo group.

I have discoveredthat when a spinning fluid is prepared by dispersingin a polyvinyl alcohol solution an emulsion or fine powder of water-insoluble polymers containing acid groups, even when the fiber is subsequently made hydrophobic by treatments such as benzalization,

and the like, no decrease in dyeabilitytakes place and the fibers exhibit excellent dyeability for the above-mentioned "ice dyes. Furthermore, the larger the particle size of the solid particles of polymer and the greater the degree of hot stretching, the better the dyeability.

The reason for the foregoing results are not fully understood. However, it is presumed that, in the case of such solid particles, the larger the size of the particles, the less the particles are affected by the polyvinyl alcohol molecule or its benzalized portion, with the result that the dyestutf can more easily permeate the fibers. In any case, since there is an existing need for polyvinyl alcohol or vinylon fibers having excellent elastic recovery and dyeability, this invention is to substantial significance since it makes it possible to achieve this objective and to provide the desired fibers conveniently and economically.

The emulsion'or fine powder of the polymers containing acid groups suitably used in accordance with the present invention is conveniently manufactured by various methods. For example, polymerizable monomers containing acid groups such as a carboxyl groups or a suite group, or their salts such as their sodium salts, ammonium salts, and the like, e.g. acrylic acid, methacrylic acid, crotonic acid, vinyl sulfonic acid, allylsulfonic acid, styrenesulfonic acid, and. their salts, are polymerized by emulsion polymerization or suspension polymerization techniques. The desired water-insoluble polymer, can also be obtained by suspension or emulsion copolymerization of the above-characterized monomers with other polymerizable monomers such as vinyl chloride, allyl chloride, vinylidene chloride, vinyl benzoate, allyl acetate, styrene, butadiene, divinylbenzene, methyl acrylate, methyl methacrylate, acrylonitrile, methyl vinylketone, and the like. Emulsion polymerization, or suspension polymerization are easily effected by conventional means, using anionic surface active agents or non-ionic surface active agents as emulsifier, and using various water-soluble polymers such as polyvinyl alcohol, gelatin, and the like, as protective colloids, if desired. The particle size of the emulsified or suspended polymer is suitably from 0.0m to a few a, e.g. 10 1 The desired emulsion or fine powder can also be produced by dissolving a water-insoluble polymer having an acid group, e.g. polymers formed from the above-mentioned monomers, in an organic solvent, and the solution is then dispersed in water in the presence of a surface active agent or protective colloid, and then the organic solvent is removed by distillation.

' Use can also be made of polymers having acid groups, which are obtained by introducing the acid group by chemical reaction eliected upon a polymer having a reactive group which can be converted to an acid group. For example, by partial saponification of methyl polyacrylate, a water-insoluble polymer having an acid group can be obtained. This reaction can be carried out af er the formation of an emulsion of the polymer or chemical reaction may be carried out prior to the formation of the emusion, the emulsion of the converted polymer then being prepared by the above-mentioned method.

Water-insoluble polymers containing an acid group are also suitably formed in emulsified or in finely divided powder form by aectalizing a water-soluble polymer, such as polyvinyl alcohol, by means of aldehydes containing acid groups such as glyoxylic acid, carboxy-acetaldehyde, azelaic aldehyde, sulfo-acetaldehyde, disulfo-acetaldehyde, 0C, or fl-propion-aldehyde, o-, m, or p-sulfobenzaldehyde, sulfonaphthaldehyde, and the like. Simultaneously with such acetalization, or before or after it, acetalization of the polymer may be effected by means of aldehydes having no acid radical such as formaldehyde, butyraldehyde, benzaldehyde, and the like, to produce water-insoluble polymers for use in accordance with this invention. In forming emulsions of polymers by this lastnamed procedure, it is advantageous to effect the reac- 'tion with high-speed agitation or to add various surface-v 7 active agents or water-soluble polymers, and the like to the reaction mixture to serve as emulsifiers or protec- In accordance with this method, particle tivel colloids. V sizes ranging from 0.1a to 10 can easily be obtained.

In the case of these acetalized polyvinyl alcohols, the

previously mentioned methods for dispersing polymers in Water may also be used toform the emulsion.

Acetalization by-means of aldehydescontaining no acid,

groups, such as those mentioned above,,-may also beeffected upon polyvinyl alcohol derivatives containing these have functional groups which are easily convertible into acid'g ronps, by {chemical reaction, or upon copolymers principally composed of vinyl alcohol and containing such convertible 'groups, such as the copolyinerizationsaponification product of allyl chloride and vinyl acetate,

The reaction to order to insolubilize such polymers. eife'ct introduction of acid groups, e.g. sulfonati-on, effected by the action or sodium sulfite on halogens, such as chlorine, is suitably "carried out While the polymer is in emulsified orfinely-divided form.

Itis preferable to use aldehydes containing acid groups I for the introduction of the acid group into polyvinyl alcohol, but such'groupsrnay be introduced by otherreactions applied to polyvinyl alcohol, e.g. oxidation by means of an oxidizing agent such as potassium :permanganate, and theplike, sulfo ethyl-etherification by means of vinylsulfonic acid, hydrolysis after carbamoylet hyl-etherification by means of acrylamide, and like known other methods for the introduction of an acid group.

In addition, the product of reaction to introduce an acid group into water-insoluble particles such as starch, e.g. ether-ification with monochloracetic acid, can also .beused. In either case, as the result of the introduction of an acid group such as the 'carboxyl or the .sulfo group, a suitable hydrophilic quality and electrical repulsion are im'parted to the polymer particles, so that the emulsion or finely-divided .powder of the polymers used hasfienhanced stability in Water and in admixture with polyvinyl-alcohol, and when they are dispersed'in the spinning fluid, theirrstability is further increased so that the spinning fluid is easily and readly filtered totacilitate spinning. However, when the content of the acid group 'is't'oo high, it may become difficult .to insolu- -bilize the polymers by reason of pronounced hydrophilic quality provided byqthe high acid group content. It is difi'lcult to define the optimum range of the acid group content because it depends upon the hydrophobic quali- -tiesof theparticular polymer and the hydrophilic quality of the'particular acid group, but the range of l-70mol :percent has beenfound to be suitable, mol percent being based :on the polymer "containing the acid group. A suitable ratio for mixing these polymers with polyvinyl alcohol to form a "Spinning fluid is 0.1-10mo1 percent;

When this ratio isused, a marked increase is'noted in thedyeability of-the resulting fibers with'respectto cation "dyes and basic dyes." Moreover, any'de'crea'se in hotwater resistance, heat resistance, mechanical properties,

and the like is held to a minimum. The particle size "centage of broken fibers and nappy fibers increases, re-

sulting in ayarn .of poorer mechanical properties. Thus, it "is desirable for the particle diameter to 'be below 3011.

It is possible to carry out spinning by means of the.

spinning fluid prepared by dispersing an emulsion or "a fine powder of the polyvinyl. alcohol derivatives with polyvinyl alcohol-by the; method of this invention, with the addition of various types of water-soluble polymers such as soluble-starch, polyvinylpyrrolid-one, aminoacetalized {polyvinyl alcohol, various kinds. of pigments such.

as titanium oxide,'and acids," alkalis, and salts such as sodium sulfate, and the' like. Accordingly, it is possible to simultaneously effect improvements in the transparency and in the form of the cross-section of thefiblersp-particularly when. the fibers areforrnedrby wet sp'innin'ge,

The fibers spun by the method ,ofthis invention may be subjected to thermalelong'ation, is. hot-stretching, heat-' treatment and .insolubil-ization treatments in the same manner as'fibers formed solely from-ordinary polyvinyl alcohol. For reflecting insolubilization, acetalization by means of aliph'atic, aromatic or aralkyl aldehydes ,is'suit ably employed. Suitable aldehyd'es. :for' this purpose include formaldehyde, acetaldehyde,= chloroacetaldehyde, IIIOII O butyraldehyde,v nonylaldehyde, benzaidehyde, chlorobenzaldehyde, l -naphthaldehyde 'sgliyox'al, :malonaldehyde, glutaraldehyde, terephthalaldehydefand like aliphat-i0, aromatic andiaraikyl.aldehydes; The fibers may alsobesubjected to treatments 'vvithginorganic re'a'gents such as titanification and chr'omin'g. Various othenknolwn insolubilization treatments may also be employed.

The invention will be further understoodfrom the fol:

Example 1 A mixture ofmethyl acrylate (7754 g), "acrylic acid (7.2 g.-), caustic soda (2 g.), polyvinyl alcohol (171g), the

anion dispersant, lat-sodium sulfosuccinic dioctyl ester (4 1 g.), potassium persu1fatef(0.5 g.) sodium bisulfite (0.3 g.) and, water (500 g.) was stirred at 60 Cifor 4 hours toefiect emulsion polymerization; 'Unreacted'substanee's: were removed by steam distillation and dialysis, and an emulsion of 9.1% concentration was obtainedin a yield This emulsion was mixed with 20% of poly-.

of 81 vinyl alcohol, and a spinning: fluid-having atotal polymer concentration of 15% wasprepared. The fluid was wetspun into a coagulation bath of sodium sulfate-in conventional manner. The fibers thus produced, were stretched 2 by 100% at 230 C., andshrun'k by 20% atv 235 C. The fibers were .then formalized in a bath consistingof formaldehyde (5%) sulfuric acid (15%), and sodium sulfate (15%) at 70 C. for one :hour. The-degree of formalization was 38 molpercent. These fibers underwent shrinkage of 3.8% when treated in boiling water .for

30min. The temperature atwhich a 10% shrinkage-oc- I curred in air (softening point) was 210C! The fiber. strengthwas 4.8 g./denier., When dyed with the basic dye methylene blue 1 (4%) and, acetic acid (1%) (per-:-

centages' based on the weight of fiber) at Cnfor 2 hours, the dye was almost completely absorbed and a saturated blue color was obtained.

Example 2 A mixture composed of688 g. :vinyl acetate, 172g. crotonic acid (20 mol percent of both monomers), partially saponified polyvinyl acetate of'a degree ofsaponification of mol per g..),..polyoxyethylene (.20. mo1.per-;

cent), lauryl ether (8,6 g), hydrogen peroxide (4 g),

sodium tartarate (1 g.)' and water (4 1.), Was subjected to emulsion polymerization at. 60 "C. for 3 hours, and was purified by steam distillation. 'Ihe:emulsion thus obtained wasmixed with 25% of polyvinylalc'ohol, and wetp g was effected in the manner described in Examp'le 1. The result was as satisfactory asthat realized by spin ning a water. solution of polyvinyl alcohol, alone, and. the

spinning operation could be performed satisfactorily. The fibers produced were heat-treated as described in Example 1. After heat-treatment as described in Example 1, some of the fibers were formalized by the procedure of Example l (Sample I). The remaining fibers were benzalized in a water solution containing benzaldehyde (2%),- sulfuric acid and methanol (30%) at 60 C. for one hour (Sample II). For the purpose of comparison, fibers were spun from a conventional polyvinyl alcohol spinning bath to which polyacrylic acid (5% based on polyvinyl alcohol), and caustic soda (50 mol percent base on polyacrylic acid) were added, and after heat-treatment as described above, the fibers were formalized (SampleIII) or benzalized (Sample IV), formalization and berizalization being effected by the procedures used in producing Samples I and II, respectively.

For the purpose of further comparison, additional fibers were spun from a 'water solution of polyvinyl alcohol alone and these fibers were heat-treated and formalized (Sample V) "or benzalized (Sample VI) as described above. The various properties of these several fibers are set ,forth below:

6 were dyed by means of Sevron Green B (4%) under the same conditions described in Example 2, whereby the fibers were dyed a bright, dark green color. The fibers showed an elasticity of 78% at an elongation of 3%, and had a feel which was very rich in elasticity.

Example 4 Example 5 Emulsion polymerization was effected by agitating a mixture composed of vinyl acetate (73 g.), allylbromide Samples Properties I II III IV V VI Carboxyl content (Based on the entire polymer con- 2.26 2.26 2.98- 2.98

tent) (mol percent).

A cetnliv iflnn Formall- Benzah- Formall- Benzall- Formall- Benzalization zation zation aztion zation zation. Degree of Acetalization (mol percent) 39 22 1 23 7 Shrinkage in boiling water (percent) 3.5 7.5 6.0- 9.1 3.0 6.5. Strength (gJdenler) 4.6 4.4 4.1 4.0. 4.9 4.6. Elasticity, (percent) (at 3% Elongation) 55 75 5 7 5 78. Dyeability 1 Saturated Saturated Saturated Light Light Stained.

. color. color. color. color color 1 Dyed with 4% Sevron Green B, or 4% Sevron Red B and 1% acetic acid (percentages based on the weight of fiber), at 80 C for 2 ours. r

1 Sample V,-- and particularly Sample VI, which is ordinary Vinylon, did not exhibit a dyeability of any practical value with the above-mentioned Sevron Colors, whereas in the case of the formalized Sample III, a saturated color was obtained, but in the benzalized Sample IV, which exhibited excellent elasticity, only a light color was obtained. In Samples I and II, produced by the method of this invention, a saturated color of practical value was obtained, and particularly in'the case of benzalized Sample II, the elasticity was also fully satisfactory.

Example 3 An aqueous solution containing polyvinyl alcohol (3%), formaldehyde (1%) andsulfuric acid (50%) was reacted at 50 C. for 2 hours with agitation at 1,000 r .p.m., and the reaction mixture was diluted to twice its volume by gradual addition of a water solution containing a dispersant (1%) at 40 C. Purification was then effected by removing unreacted substances and sulfuric acid by means'of dialysis in running water. A mixture was then formed of 3% of the finely-divided formalized polyvinyl alcohol of a degree of formalization of 50 mol percent thus obtained, sulfuric acid (10%) and usodium sulfoacetaldehyde dimethylacetal (100 mol percent based on polyvinyl alcohol), and the mixture was stirred at 70 C. for 4 hours. Following purification by means of dialysis in running water, there was obtained a stable emulsion. The degree of sulfoacetalization of this emulsion was about 10 mol percent, and the particle diameter was about 15,u.. The emulsion was mixed with 10% of polyvinyl alcohol to produce a spinning solution having a total polymer concentration of Dry-spinning was effected in conventional manner by extruding the solution through a spinning nozzle of 0.3 mm. diameter into the air. The resultant fibers were stretched at 220 C. by 400%, and then relaxed at 225 C. by 15%. Upon benzalization by the procedure described in Example 2, fibers having a degree of benzalization of 24.5 mol percent were obtained. These fibers (18.2 g.), polyvinyl alcohol (19.1 g.), ammonium persulfate (1.6 g.), sodium bisulfite (l g.), and water (600 g.) at 60 C. After about 2 hours, the emulsion gradually coagulated, forming a precipitate. After further heating for 5 hours, the precipitate was dissolved in methanol, the solution poured into water, and the solids collected by evaporation. This process was repeated and there was recovered a copolymer containing allylbromide (14.5 mol percent) in a yield. of 56%. Twenty grams of this copolymer were heated with a 15% aqueous solution of sodium sulfite g.) for 24 hours. Unreacted substances were then removed by dialysis in running water, and the product was treated as described in Example 3 to produce a stable emulsion following purification dialysis. This emulsion was mixed with 15% of polyvinyl alcohol, and the spinning fluid thus produced were wet spun in conventional manner. The fibers were heat-treated and then formalized or benzalized as described in Example 2. All of the fibers thus obtained were found to have excellent dyeability.

Example 6 V Example 7 An aqueous solution containing polyvinyl alcohol (3%) sulfuric acid (15%) and a dispersant (2%) was stirred at 60 C., and benzaldehyde (50 mol percent based on polyvinyl alcohol) and o-sulfobenzaldehyde (20 mol percent based on polyvinyl alcohol) were gradually added. The product was purified by dialysis and there was obtained an emulsion of polyvinyl alcohol acetalized by benzaldehyde and o-sulfobenzaldehyde. was mixed with 20% polyvinyl alcohol and the mixture was thenspun and the fibers were treated in the manner described in Example 2. The fibers were found ,to have excellent dyeability.

Example 8 Using an emulsion of the copolymer of acrylonitrile containing sodium vinyl'sulfonate (15 mol percent), mix-. ing with polyvinyl alcohol to form a spinning solution to form fibers,-were efie'cte'd in the manner described 'in Ex ample '1. The fibers were then subjected to'heat-treatample 1. Fibers having excellent dyeability with respect to basic dyes were obtained.

' Example 9 A water solution containing chlo'roacetaldehyde (0.5%), formaldehyde (1%), polyvinyl alcohol (3%) and sulfuric acid (50%) wasreacted and then diluted This emu-Sim.

ment and formalization following the procedure of Exin the manner in Example 3. Acetalized polyvinyl alcohol containing halogen was thus obtained, in finely=divided j form. This product was heated witha 10% aqueous solution of sodium sulfite to introduce the sulio radical, and the reaction product was purified by dialysis. Following the procedure of Example 1, the product was mixed with polyvinyl alcohol, the mixture spun, and the fibers subjected. to heat-treatment and formalization. There were obtained fibers exhibiting excellent dyeability for basic dyes.-

The surface-active or dispersing agents or dispersants and protective colloids whichare suitably employed are, in addition to those mentioned above, any of the many dispersing agents and protective colloids known to those skilled in the art of making emulsions or dispersions ofproduced by the process of this invention. The condi- Similarly, conventional dyeing techniques tions and the relative relationships, set forthiirrthe ex- 1 amples are those preferred in carrying out the process'of the invention but it will be understood that other conditions and relationships may be used within the scope of the invention.

The spinning fluids produced in accordance with the present invention areparticularly suitable for the spinning of fibers in accordance With known processes used 7 in the spinning of polyvinyl alcohol and polyvinyl alcohol derivatives, particularly the so-called wet-spinning? techniques as described, for example, in Cline et al. US. Patent 2,610,360 and Osugi etal. Patent No. 2,906,594. A11 especially preferred spinning technique is described in coperiding application Serial No. 336,166 of Tomonari et' al., filed February 10, 1956.

After formation of the fibers by wet spinning the tiles: merits can,- as mentioned, befurther treated by stretching,

heat treating, ,acetalization,:,and the like to produce fibers with desirable "and outstanding properties For .such treatments knowntechniques such as described in said patents are suitably employed.

It will alsobe-understood that various changelsfand modifications in addition to= those. indicated-above may be made inzthe embodiments herein described without.

departing from the scope of the invention as. defined in the appended claims. his intended, therefore, that all matter :contained in the foregoing description shall be interpreted as illustrative only and not as liniitative of theinvention. i

I claim:

1. Inthe manufacture ,of polyvinyl alcehol fibersgthe steps which comprise preparing an aqueops spinning i fluid a comprising a mixture of polyvinyl alcohol and a; 01 containing a sulfonic acid group s aid pqlynier :be soluble in said aqueous spinningfiuid, dispersed polymers of an ethylenically-unsaturated monomer con? taining a sulfonic acid:group,; salts thereof, copolymers thereof. with a second monomer selected from the group consisting of ,vinyl chloride, allyl .chloride vinylidenem chlorine, vinyl benzoate, allyl acetate-,;vii1yl acetate; s

rene, butadiene, divinylbenzene; :methyl acrylate, "methyl J methacrylate, acrylonitrile, and methyl vinylketone, and

polyvinyl alcohol acetalized 'bya'n aldehyde containing a sulfonic acid group, and spinning said fluid to form fibers therefrom.

2. The method as defined in claim 1 wherein the average quantity of said sulfonic acid; group 'injsaidpolyrner, is 1 to :rnole percent and the average quantity of said. polymer, in said fluid is 0.1 to 10 mole percent based on 1 the total polymer content or the fluid. I 3. The method as defined 'inclaifrl 1, wnerein sata ethylenically-unsaturated monomer containing a sulfnic acid group is amonomer selected from the group consisting of vinylsulfonic acid, allyls'ulfonic acid, and Sty-1 renesulfonic'acid.

7 References Cited by transient-er UNITED: STATES PATENTS 2,169,250 8/1939 rzard etal 264-185, 2,236,061 3/1941: Izard et al'. can--1; .18L54 2,895,786 7/1959 Shlack 18 54 OTHERi REFERENCES Hackhs. Chemical Dictionary, 3rd ed.,. page 743 (Mebrow Hill Book Co., Inc.).

MURRAY TIELMAN, Primary Examiner. D. ARNOLD, L. J. YBERCOVITZ, Examiner's.

3 d aqueouspolyvinyl alcoholspinning fluid ifinely div ide 'd form and selected from the. group consisting of homo? l 

1. IN THE MANUFACTURE OF POLYVINYL ALCOHOL FIBERS, THE STEPS WHICH COMPRISE PREPARING AN AQUEOUS SPINNING FLUID COMPRISING A MIXTURE OF POLYVINYL ALCOHOL AND A POLYMER CONTAINING A SULFONIC ACID GROUP, SAID POLYMER BEING INSOLUBLE IN SAID AQUEOUS SPINNING FLUID, DISPERSED IN SAID AQUEOUS POLYVINYL ALCOHOL SPINNING FLUID IN FINELY DIVIDED FORM AND SELECTED FROM THE GROUP CONSISTING OF HOMOPOLYMERS OF AN ETHYLENICALLY-UNSATURATED MONOMER CONTAINING A SULFONIC ACID GROUP, SALTS THEREOF, COPOLYMERS THEREOF WITH A SECOND MONOMER SELECTED FROM THE GROUP CONSISTING OF VINYL CHLORIDE, ALLYL CHLORIDE, VINYLIDENE CHLORINE, VINYL BENZOATE, ALLYL ACETATE, VINYL ACETATE, STYRENE, BUTADIENE, DIVINYLBENZENE, METHYL ACRYLATE, METHYL METHACRYLATE, ACRYLONITRILE, AND METHYL VINYLKETONE, AND POLYVINYL ALCOHOL ACETALIZED BY AN ALDEHYDE CONTAINING A SULFONIC ACID GROUP, AND SPINNING SAID FLUID TO FORM FIBERS THEREFROM. 